Dying Light's initial release came out at the perfect time. It really capitalized on the cultural obsession with zombies. I sort of understood it, and I enjoyed it too, but I never really found "my" zombie thing until I saw Dying Light.
The gradual increase from weak and incompetent at fighting, slow and awkward at parkour, to chopping zombies in half with one strike, and passing over buildings like water, is so incredibly satisfying. You really do go from an incompetent feeling nobody to feeling like a living legend.
The gameplay and exploration is where the game shines the most. Exploring Harran, gathering supplies, and taking time to learn where things are in the map when you need a re-up makes the world quickly become easy to memorize, and its small size and the movement being really fun make traversal a joy.
The extra difficulty modes and free added content added a lot of replay value for me. Night runs were also a brilliant idea, letting you explore in the dead of night with more zombies shambling around and the dangerous volatiles, which will give you a progressively more hectic chase until you reach a safe zone or the sun rises. At night, your XP is also doubled, so it's an extremely smart way of having a built in difficulty that you can easily opt in and out of. Much like zombies themselves, Dying Light will have its period of dormancy, but it always seems to come back for me.

Good story.
Action
A game about a zombie apocalypse. This theme has become quite boring for players, but in Dying Light it is executed superbly. Hordes of simple zombies, mutants, huge zombies with clubs. Cool.
Parkour. If it weren't for parkour, the game wouldn't be so rich. I repeat, you can climb anywhere. Parkour also includes tests in which you need to overcome obstacles against time.
Graphic arts. There is nothing to say here, she is gorgeous.Crafting system. An important point for any survival. You can craft weapons (guns, one-handed/two-handed, throwing weapons, grenades, etc.), first aid kits, master keys for breaking into chests and safes, and much more. You can also add some effect to the weapon, such as razor, or use the “Fire Blade” recipe to create the Sword of Gabriel. And this is good.
Perks. Perks add even more action to the game. Jump over enemies, crush heads with one kick, create a tornado with your two-handed hammer, and 101 more ways to kill zombies.
Cooperative. What can I say, it’s cool, as they say, one head is good, but four in the world of zombies is even better.
Achievements and trading cards, there is a Russian language. It wouldn't happen.

O gameplay é o que mais se destaca nesse jogo, porque a história é bem ruinzinha.

Na DLC The Following, a experiência do jogo melhora consideravelmente e ali, talvez, alcança o seu verdadeiro potencial. O ruim é que por ser numa outra região (e até acessada por outro menu), a volta para a campanha principal com as novas armas podem ficar meio estranhas.

PS.: Um pequeno destaque para a DLC Hellraid, que parece mais um minigame mas eu curti a temática com a mistura do gameplay de Dying Light. É divertida.